Statistics from district attorneys across the state on arrests and charges appear to back that up.

Yet law-enforcement officers who interact with students each school day, and whose job it is to intervene and report on drug use by teens, offer a starkly different perspective. And a Denver Post review of available data found shortcomings in how marijuana cases are handled and tracked in Colorado schools, raising questions about the data's reliability.

School resource officers in Colorado – police who are assigned to public schools – say that based on their observations, use among students has increased in recent years. What has changed, they say, is how youths are disciplined in school for marijuana violations and how statewide data on violations is collected.

These officers say they are issuing fewer tickets for marijuana infractions today than they would have without those changes, which include a 2012 law that did away with zero tolerance toward pot in Colorado schools and a policy revision that allowed districts and individual schools to decide how to deal with the problem and its discipline.

"I tend to believe we'd be issuing many more citations, and you'd most certainly see an increase in that," said Stacey Collis, a Lakewood police officer who is president of the Colorado Association of School Resource Officers. "Perhaps it's a perfect storm, with different responses from the schools, with some handling it the same as always, and others sitting back on a petty offense, not reporting it or dealing with it on their own."